The formation of color photographic images by the image-wise coupling of oxidized primary aromatic amino developing agents with color forming or coupling compounds to form indoaniline. indophenol, and azomethine dyes is well known. In these processes, the subtractive process of color formation is ordinarily used, and the image dyes customarily formed are cyan, magenta, and yellow, the colors that are complementary to the primary colors, red, green, and blue, respectively. Usually phenol or naphthol couplers are used to form the cyan dye image; pyrazolone or cyanoacetyl derivative couplers are used to form the magenta dye image; and acylacetamide couplers are used to form the yellow dye image.
In these color photographic systems, the color-forming coupler may be either in the developer solution or incorporated in the light-sensitive photographic emulsion layer so that, during development, it is available in the emulsion layer to react with the color developing agent that is oxidized by silver image development. Diffusible couplers are used in color developer solutions. Nondiffusing couplers are incorporated in photographic emulsion layers. When the dye image formed is to be used in situ; couplers are selected which form non-diffusing dyes. For image transfer color processes, couplers are used which will produce diffusible dyes capable of being mordanted or fixed in the receiving sheet.
Photographic color elements often utilize silver halide emulsions of the high bromide type, including silver bromide, silver bromoiodide and silver chlorobromide emulsions. However, as explained in Atwell, U.S. Pat. No. 4,269,927, issued May 26, 1981, high chloride silver halide photographic elements--that is, elements in which the silver halide grains are at least 80 mole percent silver chloride--possess a number of highly advantageous characteristics. For example, silver chloride possesses less native sensitivity in the visible region of the spectrum than silver bromide, thereby permitting yellow filter layers to be omitted from multicolor photographic elements. Furthermore, high chloride silver halides are more soluble than high bromide silver halides, thereby permitting development to be achieved in shorter times.
Photographic color developing compositions used heretofore, have typically been adapted for use with high bromide silver halide photographic elements. These conventional developing compositions can be used with high chloride silver halide photographic elements, but, in general, they tend to give less than satisfactory results. For example, they typically contain restraining agents such as potassium bromide, which exert too great a retardation effect on development for satisfactory use with high chloride silver halide elements. Moreover, they typically contain hydroxylamine, or a water-soluble acid salt thereof, which functions as an anti-oxidant and thereby serves to protect the primary aromatic amino color developing agent against oxidation. Use of hydroxylamine, or a water-soluble acid salt thereof, is disadvantageous, however, since it tends to act as a scavenger which reduces oxidized color developing agent before it can react with coupler to form dye. It also acts as a developing agent which competes with the color developing agent unless it is adequately restrained by bromide. In addition to hydroxylamine, or a water-soluble acid salt thereof, developing compositions heretofore used with high bromide silver halide elements often contain substantial concentrations of sulfite to also provide protection against oxidation of the developing agent. The sulfite, which is typically utilized in the form of an alkali metal sulfite or bisulfite, functions to sulfonate oxidized color developing agent and, when used in sufficient concentration, its competition with coupler for oxidized color developing agent seriously affects dye formation.
Included among the numerous patents which describe photographic color developing compositions, of the type typically used with high bromide silver halide elements, are the following:
Kridel, U.S. Pat. No. 2,875,049, issued Feb. 24, 1959.
Tassone, U.S. Pat. No. 3,462,269, issued Aug. 19, 1969.
Anselm, U.S. Pat. No. 3,489,566, issued Jan. 13, 1970.
Heilmann, U.S. Pat. No. 3,746,544, issued July 17, 1073.
Brown, U.S. Pat. No. 3,839,045, issued Oct. 1, 1974.
Frank, U.S. Pat. No. 3,994,730, issued Nov. 30, 1976.
Shimamura et al, U.S. Pat. No. 4,083,723, issued Apr. 11, 1978.
Case et al, U.S. Pat. No. 4,170,478, issued Oct. 9, 1979.
Case, U.S. Pat. No. 4,252,892, issued Feb. 24, 1981.
Vincent et al, U.S. Pat. No. 4,264,716, issued Apr. 28, 1981.
Cappel, U.S. Pat. No. 4,394,440, issued July 19, 1983.
Kapecki et al, U.S. Pat. No. 4,414,307, issued Nov. 8, 1983.
Twist et al, U.S. Pat. No. 4,482,626, issued Nov. 13, 1984.
In light of the above, it is clear that there is a need in the art to provide photographic color developing composition and photographic processes which are especially adapted for use with high chloride silver halide elements if the inherent advantages of such elements are to be most fully realized. It is toward the objective of filling such need that the present invention is directed.